I believe Emergencies R Us said that it enables everyone to practise and yes that includes D&D. Not much use having a bunch of emergency controllers who the first time that they respond to an emergency it is a real one.
I think everyone agrees that a VHF PETF is required. The only way for that to happen is, rather than talking about it on Prune, talking officially to the CAA, NATS, SRG etc. There is no doubt that there is a negative impact upon flight safety through the use of 121.5 to practise on. The military realized that sometime ago and lo and behold, once enough pilots had complained, pointing out the flight safety implications of what was happening, PETF was born.
DFC, I think that your rather bald statement that the military system has had more investment is a bit off the mark. The UHF system was initially devized, using a lot of existing transmitter and receiver sites, to provide coverage across the UK, specifically over the North Sea to enable D&D to find Lightning pilots who kept ejecting from their aircraft. The civil system has only ever been about keeping light aircraft pilots outside the London TMA specifically and CAS generally. It was never supposed to mirror the military system and shouldn't be seen in that light. I think that the guys up in D&D might also raise issue with the level of investment that's been made in the system itself, when you look at the kit that they work with!